Giant Trevally (GT) or Kuwe Gerong

Giant Trevally or commonly called the GT and in Indonesia called Kuwe Gerong is a highly sought after fish by anglers because of its power is very strong. These fish can be obtained by trolling, jigging and popping.

The giant trevally is the largest member of the genus Caranx, and the fifth largest member of the family Carangidae (exceeded by the yellowtail amberjack, greater amberjack, leerfish and rainbow runner), with a recorded maximum length of 170 cm and a weight of 80 kg.

Specimens this size are very rare, with the species only occasionally seen at lengths greater than 80 cm. It appears the Hawaiian Islands contain the largest individuals, where indivduals over 100 lbs are common. Elsewhere in the world, only three individuals over 100 lbs have been reported to the IGFA.

The giant trevally is similar in shape to a number of other large jacks and trevallies, having an ovate, moderately compressed body with the dorsal profile more convex than the ventral profile, particularly anteriorly. 

The dorsal fin is in two parts, the first consisting of 8 spines and the second of 1 spine followed by 18 to 21 soft rays. The anal fin consists of 2 anteriorly detached spines followed by 1 spine and 15 to 17 soft rays. 

The pelvic fins contain 1 spine and 19 to 21 soft rays. The caudal fin is strongly forked, and the pectoral fins are falcate, being longer than the length of the head. 

The lateral line has a pronounced and moderately long anterior arch, with the curved section intersecting the straight section below the lobe of the second dorsal fin. The curved section of the lateral line contains 58-64 scales while the straight section contains 0 to 4 scales and 26 to 38 very strong scutes.

The chest is devoid of scales with the exception of a small patch of scales in front of the pelvic fins. The upper jaw contains a series of strong outer canines with an inner band of smaller teeth, while the lower jaw contains a single row of conical teeth. 

The species has 20 to 24 gill rakers in total and there are 24 vertebrae present. The eye is covered by a moderately well developed adipose eyelid, and the posterior extremity of the jaw is vertically under or just past the posterior margin of the pupil. 

The eye of the giant trevally has a horizontal 'streak' in which ganglion and photoreceptor cell densities are markedly greater than the rest of the eye. It is believed this allows the fish to gain a panoramic view of its surroundings, removing the need to constantly move the eye. This in turn will allow easier of detection of prey or predator in that field of view.

At sizes less than 50 cm, the giant trevally is a silvery-grey fish, with the head and upper body slightly darker in both sexes. Fish greater than 50 cm show sexual dimorphism in their colouration, with males having a dusky to jet black body, while females are a much lighter coloured silvery grey. 

Individuals with a darker dorsal colouration often also display striking silvery striations and markings on the upper part of their body, particularly their back. 

Black dots of a few millimetres in diameter may also be found scattered all over the body, although the coverage of these dots varies between widespread to none at all. All the fins are generally light grey to black, although fish taken from turbid waters often have yellowish fins, with the anal fin being the brightest. 

The leading edge and tips of the anal and dorsal fins are generally lighter in colour than the main fin. There is no black spot on the operculum. Traces of broad cross-bands on the fish's sides are occasionally seen after death.
A mature male giant trevally showing the black colouration common in these older fishThe giant trevally is widely distributed throughout the tropical and subtropical waters of the Indian and Pacific Oceans, ranging along the coasts of three continents and many hundreds of smaller islands and archipelagos.

In the Indian Ocean, the species easternmost range is the coast of continental Africa, being distributed from the southern tip of South Africa north along the east African coastline to the Red Sea and Persian Gulf. The giant trevally's range extends eastwards along the Asian coastline including Pakistan, India and into South East Asia, the Indonesian Archipelago and northern Australia. 

The southernmost record from the west coast of Australia comes from Rottnest Island, not far offshore from the capital city of Perth. Elsewhere in the Indian Ocean, the species has been recorded from hundreds of small island groups including the Maldives, Seychelles, Madagascar and the Cocos (Keeling) Islands.

The giant trevally is abundant in the central Indo-Pacific region, found throughout all the archipelagos and offshore islands including Indonesia, Philippines and Solomon Islands. Along continental Asia, the species has been recorded from Malaysia to Vietnam, but not China. Despite this, its offshore range does extend north to Hong Kong, Taiwan and southern Japan. 

In the south, the species reaches as far south as New South Wales in Australia and even to the northern tip of New Zealand in the southern Pacific. Its distribution continues throughout the western Pacific including Tonga, Western Samoa and Polynesia, with its westernmost limits known to be the Pitcairn and Hawaiian Islands.

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